Madonna belted out some of her biggest hits as she treated people in New York to a surprise outdoor concert in support of Democratic presidential nominee Hillary Clinton.

About 300 people jammed into Washington Square Park, in the heart of Manhattan, to watch the pop singer perform Express Yourself, Don't Tell Me, Imagine, Like A Prayer and If I Had A Hammer while they sang along.

Madonna opened the 30-minute performance by urging the crowd to vote on Tuesday.

"This is a concert that is about unifying us, and it's about keeping America great, not making America great again," she said.

"Tomorrow we're going to keep America great. We're going to elect a president that does not discriminate."

As she finished the concert, she again urged the growing crowd to go to the polls and vote for Mrs Clinton.

She said: "New York! Tomorrow is the big day. Are you listening? Do we want Donald Trump to be president?"

The crowd roared back: "No!"

"Do we need Hillary Clinton?"

"Yes!"

Some in the crowd were just as excited to vote for Mrs Clinton as they were to see a Madonna performance.

"It's really exciting the enthusiasm to elect the first woman president, to elect a president who will fight for LGBT rights, fight for women's rights and to move America forward," said Zach Baum, a 23-year-old from Long Island.

"It's really a choice about who we are as a nation."

For Sara Bellis, a 34-year-old from the Bronx who wore a yellow "Hillary" badge, the election of Mrs Clinton has been a long time coming.

"I've been a Hillary fan since I was in elementary school," she said. "Now I have three kids, and I think far and away she has the best chance of creating the kind of world I want them to have."